Since ocean occupies seven tenths of the earth surface, marine transportation plays an important role in the traffic of the world trade. The revolutionary containerized shipment replaces the conventional means of transport to a very great extent except carriage of bulk cargo, such as coal, grains, crude oil and a few other commodities.
The United States of America is, so far, the biggest exporting country of grains in the world. She sells huge quantity of agricultural products in bulk to the Far Eastern nations, such as the Republic of China, Japan, Korea, USSR, Red China etc. The quantity of the export increases each year and is mostly carried to the destination by the conventional bulk carriers although small shipments of the grains are effected by the bulk containers, the number of which is quite limitted. The ordinary general utility dry cargo containers are not suitable for the carriage of the bulk cargo. Tremendous number of such containers must be carried back to the ports, without cargo loaded, in Far-East where the export cargoes await shipment. This is the waste of energy.
It is also an universal knowledge that bulk carriers are serviced, not regularly but in tramp service. The cargo flow is usually affected by availability of the carriers which greatly influence the economical impact of the commodity stock and flow. The assumption of this invention to utilize the empty general dry cargo containers having to be returned to the various ports is to save cost of the shipping operators, with little modification applied to the containers when they are manufactured. New containers must be ordered when old ones reach the end of the serviceability. This invention could be applied when order for new containers is placed.